disease management jason brock uga department of plant pathology
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Disease Management
Jason Brock
UGA Department of Plant Pathology
I. Survey
II. Chemical Options
III. 2004 Fungicide TrialsA. DMI Sensitivity
B. Stratego timing
C. Orbit/Super Tin co-pack
IV. Tim Brenneman’s Research
I. Fungicide Survey
2004 PECAN FUNGICIDE SURVEY COUNTY: ACRES: ____________ SPRAYER: ____________________________________________________ A) Abound
B) Agri Tin
C) Elast (Dodine)
D) Elast & TPTH
E) Elast & Enable
F) Enable
G) Enable/AgriTin co-pack
H) Headline
I) Orbit/Super Tin co-pack
J) Propimax
K) Stratego
L) Sulfur
M) Super Tin
N) Topsin-M
---------------------------------------------------------------------------------------------------------------- SPRAY 1 SPRAY2 SPRAY3 SPRAY 4 SPRAY5 Pre-pollination: (Bud break through nut set) Post-pollination: (Nut set to shell hardening) After shell hardening: ---------------------------------------------------------------------------------------------------------------- Did you use aerial application of fungicides? YES NO
o If yes, what volume of water was used? _______ _______
What is your preferred timing for fungicide sprays? DAY NIGHT Comments:
II. Chemical Options
Triphenyltin hydroxide (TPTH)
StrobilurinsSterolInhibitors (DMI’s)
Stratego
Super-Tin AgriTin
Propimax
Orbit EnableAbound Headline
Elast
Topsin-M
Sulfur
Triphenyltin hydroxide (TPTH)
StrobilurinsSterolInhibitors (DMI’s)
Elast (Dodine)
Low risk for resistance. Good on nut scab Weaker on leaf scab and other foliar diseases.
Moderate risk for resistance. Very good for leaf scab and other foliar diseases. Switch to other chemistry OR use reduced rate full season.
Less risk for resistance than DMI’s and Strobilurins. Best suited for June-July sprays. Works well tank mixed with TPTH or Enable.
Moderate/High risk of resistance. Very good for leaf scab and
other foliar diseases.
Resistance Management
• Sterol Inhibitors (DMIs)– Use reduced rate full season– If used alone, switch to different chemistry
• Strobilurins– Do not make more than 3 total applications.
• Elast (dodine)– Do not use full season
Management of Pecan Scab
Pre-pollination Post-pollinationAfter shell hardening
Agri Tin / Super Tin
Orbit/Super Tin co-pack ▌ Enable/Agri Tin co-pack
Abound / Headline
Elast
Enable / Propimax
Enable + Elast
TPTH + Elast
Stratego Stratego
III. Fungicide Trials
Stratego Timing Trials
Where does Stratego fit best?
April May June July August Sept.
Pre-pollination Post-pollination After 15 August
Orbit/Super Tin co-packStratego 10.0 oz/A
Stratego 10.0 oz/AOrbit/Super Tin co-pack
Stratego 10.0 oz/AOrbit/Super Tin co-pack Orbit/Super Tin co-pack
Stratego applied in blocks of 3 sprays.
Randomized Complete Block with 4 reps.
Locations
Nut Scab Data• Incidence = % nuts with any scab.• Severity = mean % of shuck surface covered
with scab
• Damage = % of nuts with 25% or more of the shuck covered with scab
Nut Quality Data• Length• Nuts per pound• Percent Kernel
Sumter CountyNut Scab Data
0102030405060708090
100
INC SEV DAM
NT
PRE
POST
ASHa
b a
b b b bb
a
b
b
b
Lanier CountyNut Scab Data
0102030405060708090
100
INC SEV DAM
NT
PRE
POST
ASH
a
b
a
b b
bb b
Mitchell CountyNut Scab Data
0102030405060708090
100
Incidence Severity Damage
NT
PRE
POST
ASH
a
c
a
b
c
b
c
d
Nut Quality (Stratego Trials)
• All spray programs significantly improved nut quality compared to the non-treated trees.
• There were no significant differences between spray programs.
No Fungicide A
Pre-pollination B
Post-pollination B
After shell hardening B
Length
Nuts/lb
% Kernel
Summary
• Late season applications of Stratego did not improve nut quality.
• In Mitchell Co., pre-pollination and post-pollination applications of Stratego resulted in lower nut scab than after shell hardening applications.
Where does Stratego fit best?
April May June July August Sept.
A.Great for control of leaf scab.B.Other options exist for nut scab.
Post-pollination application was the best option at one location.
DMI Sensitivity Trials
DMI Chemicals DMI Products
• Propiconazole– Orbit– Propimax– ½ of Stratego
• Fenbuconazole– Enable
• Propimax
• Enable
• Enable/Agri Tin
• Orbit/Super Tin
• Stratego
Potential Problem
• DMI’s have a narrow mode of action.
• There are documented cases where fungi have become resistant.
• Resistance will develop gradually over time.
Where do we stand?
• DMI’s used on pecan in Georgia since 1988.
• Isolates collected and assayed in 1995, 2002, and 2003.– Commercial and research orchards
– With and without DMI history
Where do we stand?
• Since 1995, sensitivity (in laboratory) to DMI’s has declined in a majority of the orchards.
• Wide-spread control failures have not been reported.
Questions Raised
• What is the impact on reduced-rate DMI programs?
• What is the best use of DMI’s?
• What is the long-term future of DMI’s?
2004 Trials
• The objective was to examine the effectiveness of full and reduced rates compared in orchards with ‘high’ and ‘low’ sensitivities.
DMI Trial Locations
Spray Program*
Bud break – 1 June
• 1st spray: Agri Tin (2.34 lb per 500 gal)
• 2nd spray: Headline (30 oz per 500 gal)
• 3rd spray: Headline (30 oz per 500 gal)
• 4th spray**: Agri Tin (2.34 lb per 500 gal)
** If needed
* Not recommended. A non-DMI program was needed.
Spray ProgramJune – July (4 Sprays)
• Full-rate DMI– Enable (40 oz/500 gal) + 80/20 surfactant
• ½ Rate Mix DMI– Agri Tin/Enable co-pack (1 pack/500 gal)
• Non-DMI– Elast 400 (1 gal/500 gal) +
Agri Tin (1 single pack/500 gal)
Rest of season – All treatments
• Agri Tin (1 double pack per 500 gal)
Nut Scab Summary
0102030405060708090
100
High Low High Low
Full
1/2 Mix
Non-DMI
Check
INCIDENCE SEVERITY
Nut Quality Summary
0
10
20
30
40
50
60
70
80
High Low High Low High Low
Full
1/2 Mix
Non-DMI
Check
LENGTH NUTS/LB % KERNEL
2004 DMI Trials• Differences in treatments seem do not appear to
be due to failure of DMI chemistry.• Similar separations in high and low sensitivity
locations.
Full-rate DMI Enable (40 oz/500 gal) + 80/20 surfactant
½ Rate Mix DMI Agri Tin/Enable co-pack (1 pack/500 gal)
Non-DMI Elast 400 (1 gal/500 gal) + Agri Tin (1 single pack/500 gal)
• Reduced sensitivity to DMI’s is a concern.– Reduction in sensitivity has been documented
in the laboratory.– Has been documented with other crops.
• Data from field trials does not indicate a failure of DMIs in disease management.
• Resistance management will be important to preserve the use of DMI’s.
Orbit/Super-TinCo-pack Trial
Change in Orbit/Super-Tin Co-pack
Super-Tin
5.0 oz/a
Orbit
4.0 oz/a
Super-Tin
3.75 oz/a
Orbit
4.0 oz/a
AgriTin
3.75oz/a
Enable
4.0 oz/a
Super-Tin
3.75oz/a
Orbit
4.0 oz/a
Propiconazole less effective than fenbuconazole on nut scab.
Needed?
• Location – Dougherty Co.
• All replications received the same pre-pollination sprays.
• Test treatments began in June.I. New co-pack [Orbit 4.0 oz + Super-Tin 3.75]*
II. Old co-pack [Orbit 4.0 oz + Super-Tin 5.00]
III. New co-pack + [Orbit 4.0 oz + Super-Tin 5.63]
* Rate per acre
0102030405060708090
100
INC SEV DAM
NT
New
Old
New ++
a
a
b
c
b
c c
c
• For optimal control of nut scab, spike the Orbit/Super-Tin co-pack up to a minimum of 5.0 oz per acre.
• New packages of Super-Tin available.
• Cost backed out of product.
• ‘New’ Orbit/Super-Tin co-pack will be fine for control of leaf scab.
Acres @
100 gals/A
Orbit/Super
-
Tin co-pack
Super Tin
2.34 lb package
‘New’ Super Tin
1.172 lb package
Final Tank Mix Acre Rates
10 Acres(1000 gals
water)2 packets
4 oz Orbit +
3.75 oz Super Tin
10 Acres(1000 gals
water)2 packets 1 packet
4 oz Orbit +
7.5 oz Super Tin
10 Acres(1000 gals
water)2 packets 1 packet
4 oz Orbit +
5.63 oz Super Tin
10 Acres(1000 gals
water)2 packets 2 packets
4 oz Orbit +
7.5 oz Super Tin
5 Acres(500 gals water)
1 packets4 oz Orbit +
3.75 oz Super Tin
5 Acres(500 gals water)
1 packets 1 packet4 oz Orbit +
7.5 oz Super Tin
Dupont Table
IV. Tim Brenneman Research
1. Desirable Fungicide Test
2. Wichita Test
Desirable Fungicide TrialTreatment Rate/A INC SEV
Enable 2F +
Elast 400F
4.0 fl oz
25.0 fl oz 67 b 3 e
Enable 2F +
Super Tin 80 WP
4.0 fl oz
5.0 oz 80 b 9 cd
Exp A +
Elast 400F
9.0 fl oz
25.0 fl oz 92 a 10 cd
Exp A +
Super Tin 80 WP
9.0 fl oz
5.0 oz 100 a 15 b
Exp B +
Elast 400F
9.0 fl oz
25.0 fl oz 87 a 7 de
Exp B +
Super Tin 80 WP
9.0 fl oz
5.0 oz 92 a 12 bc
Nontreated --- 100 a 60 a
Desirable Fungicide Trial
Treatment Rate/A INC SEV
Enable 2F +
Elast 400F
4.0 fl oz
25.0 fl oz67.2 b 3.0 b
Enable 2F +
Elast 400F
6.0 fl oz
25.0 fl oz42.2 c 1.9 b
Enable 2F +
Elast 400F
4.0 fl oz
37.5 fl oz42.2 c 2.3 b
Enable 2F +
Elast 400F
6.0 fl oz
37.5 fl oz45.3 c 2.9 b
Nontreated ---- 100 a 59.8 a
Desirable Fungicide Test
• Moderate leaf scab– All treatments worked well.
• Moderate nut scab– Elast 25 oz was a little stronger partner than
Super Tin 5.0 oz– No real gain from ‘spiked’ tank mixes
(Enable/Elast)
Wichita Fungicide Trial
Treatment Rate/A INC SEV
Exp A +
Elast 400F
9.0 fl oz
25.0 fl oz 100 31 d
Exp A +
Super Tin 80 WP
9.0 fl oz
5.0 oz 100 37 cd
Exp B +
Elast 400F
9.0 fl oz
25.0 fl oz 100 47 c
Exp B +
Super Tin 80 WP
9.0 fl oz
5.0 oz 100 62 b
Nontreated --- 100 98 a
Wichita Fungicide Trial
Treatment Rate/A INC SEV
Enable 2F +
Elast 400F
4.0 fl oz
25.0 fl oz100 46 b
Enable 2F +
Elast 400F
6.0 fl oz
25.0 fl oz100 36 b
Enable 2F +
Elast 400F
4.0 fl oz
37.5 fl oz100 19 c
Enable 2F +
Elast 400F
6.0 fl oz
37.5 fl oz100 22 c
Nontreated ---- 100 98 a
Wichita Fungicide Test
• Moderate leaf scab– All treatments worked well.
• Heavy nut scab– Stratego looked great– Elast 25 oz was a little stronger partner than
Super Tin 5.0 oz– ‘Spiking’ with extra Elast gave more benefit
than with extra Enable
No matter what fungicides you choose, remember that good
coverage is critical.
• Speed
• Sprayer calibration– Misdirected– Weak air blast
• Overcrowding
Management of Pecan Scab
Pre-pollination Post-pollinationAfter shell hardening
Agri Tin / Super Tin
Orbit/Super Tin co-pack ▌ Enable/Agri Tin co-pack
Abound / Headline
Elast
Enable / Propimax
Enable + Elast
TPTH + Elast
Stratego Stratego
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